Projection screens

ABSTRACT

A projection screen affording wide angle viewing comprises a backing with a relfective hairline surface, with a matt overlay of transparent material consisting of a coating of a pigmented solution of a modified vinyl acetate/vinyl alcohol copolymer in a mixture of ketones and hydrocarbons to afford a sharp and brilliant picture in daylight, or with an overlay consisting of a transparent plastics film having a brushed finish on the surface remote from the backing, with the lines of both materials extending in the same direction to afford even wider angle viewing in subdued lighting or total darkness.

United States Patent 11 1 Coulthard [111 3,811,750 [451 May 21, 1974PROJECTION SCREENS [75] Inventor: James Albert Coulthard, Sheffield 10,England [73] Assignees: Marie Luise Batzner Coulthard;

David Malcolm Pearson, both of Sheffield, England [22] Filed: 'July 18,1972 [21] Appl. No.: 272,868

[52] U.S. Cl. 350/117, 350/129 [51] Int. Cl. G03b 21/60 [58'] Field ofSearch 350/128, 129, 117, 126

[56] References Cited UNITED STATES PATENTS 2,934,997 5/1960 Harkness350/126 3,679,451 7/1972 Marks et al 350/126 X 3,507,548 4/1970 Hoffmanet al... 350/117 1,854,864 4/1932 Semenity 350/117 3,653,740 4/1972Ogura et a]. 350/117 Hugel 350/117 2,529,701 11/1950 Maloff 350/1282,875,087 2/1959 Crandon 350/129 X 2,928,131 3/1960 Mahler 350/117Primary Examiner-Monroe l-l. Hayes Assistant Examiner'E. M. BeroAttorney, Agent, or Firm-Lowe, King & Price [5 7] ABSTRACT A projectionscreen affording wide angle viewing comprises a backing with arelfective hairline surface, with a matt overlay of transparent materialconsisting of a coating of a pigmented solution of a modified vinylacetate/vinyl alcohol copolymerin a mixture of ketones and hydrocarbonsto afford a sharp and brilliant picture in daylight, or with an overlayconsisting of a transparent plastics film having a brushed finish on thesurface remote from the backing, with the lines of both materialsextending in the same direction to afford even wider angle viewing insubdued lighting or total darkness.

16 Claims, 6 Drawing Figures PROJECTION SCREENS This invention relatesto projection screens for slides or other stills, and films.

One object of the invention is to provide a projection screen affordingwide angle viewing.

Another object is to provide a projection screen giving a sharp andbrilliant picture even without subduing the lighting of the space inwhich the screen is located, i.e., a daylight screen affording highillumination or brilliance and clear definition or resolution of thepicture.

Yet another object is to provide a projection screen affording very wideangle viewing in subdued lighting or total darkness.

According to the present invention, a projection screen comprises abacking with a reflective hairline surface, to afford wide angleviewing, and a matt overlay of transparent material, into which thepicture is reflected and retained.

For a daylight screen the matt overlay comprises a pigmented solution ofa modified vinyl acetate/vinyl alcohol copolymer in a mixture of ketonesand hydrocarbons of the type disclosed for example in US. Pat. No.2,934,997. The reflective hairline surface affords wide angle viewing ina direction perpendicular to the lines (which, therefore, are usuallyemployed in a vertical direction) of a sharp and brilliant pictureresulting from the thinness of the coat of pigmented polymer into whichthe picture is reflected. The pigmented copolymer may be applied byspraying, roller coating, curtain coating, reverse roll coating, orgravure printing, but whatever the manner of application the coat willbe appreciably thinner thanplastics films hitherto laminated to or onreflective surfaces for this purpose and, therefore, the pigmentedcopolymer coat will absorb less light than plastics films, withconsequent improvement in the definition of the picture. One pigment,which affords the desired picture retention, is preferably finelydivided silica, or finely divided silica coated with stearate.

For a screen for use in subdued lighting or total darkness, the mattoverlay comprises a transparent plastics film having a brushed finish onthe surface remote from the backing withthe reflective hairline surface,with the lines of both materials extending in the samedirection. Thecombination of the reflective hairline surface and the brushed-silkfinish aligned in the same direction affords a brilliant picture withwide angle viewing (i.e., anything up to 45) either way perpendicular tothe lines (which, therefore, areusually employed in a verticaldirection), and the brushed surface creates warm tones withoutdetracting from the definition.

In either screen, the backing may be sheet metal, e.g., aluminium, onesurface of which is scratched in parallel lines to provide thereflective hairline surface; or it may be a rigid sheet one surface ofwhichis scratched in parallel lines to provide a hairline surface whichis vacuum coated with a reflective metal, e.g., aluminiumjor it maybe arigid sheet one surface of which is vacuum coated with a reflectivemetal, e.g., aluminium, and the coated surface scratched in parallellines to provide a hairline surface. Preferably, however, the backingcomprises plastics film, e.g., polyester film, one surface of which ismechanically brushed to provide a hairline surface which isvacuum coatedwith a reflective metal, e.g., aluminium, the backing being suitable forattach- EXAMPLES The invention will now be described further byreference to examples and to the accompanying drawings, in which:

FIG. 1 is a general view of a portion of a daylight screen according tothe invention, greatly exaggerated as to thickness;

FIG. 2 corresponds to FIG. I but shows a portion of a screen accordingto the invention for use in subdued lighting or total darkness;

FIG. 3 is a section through a rigid screen utilising the material ofFIG. 1, or the material of FIG. 2;

FIG. 4 corresponds to FIG. 1 but shows the daylight screen adhesivelysecured to a rigid support; I

FIG. 5 is a similar illustration to FIG. 4 but shows portion of a rollscreen; and

FIG. 6 is a diagram showing the test layout for comparison of theillumination or brilliance of a daylight screen according to theinvention with that of a standard matt surface screen.

In FIG. 1 a portion 1 of a daylight screen comprises a backing 2consisting of Melinex polyester film, 0.001 inch thick mechanicallybrushed on one side 3 to provide a hairline surface, which is vacuumcoated with aluminium, at 1.5 to 2.0 ohms, and then gravure printed witha pigmented solution of a modified vinyl acetate/vinyl alcohol copolymerin a mixture of ketones and hydrocarbons, the pigment being finelydivided silica coated with stearate, the quantity of dried pigmentedcoat being 7 to l0 grams per square metre.

The reflective hairline surface 3 affords wide angle viewing in adirection perpendicular to the lines (which, therefore, are usuallyemployed in a vertical direction) of a sharp and brilliant pictureresulting from the thinness of the coat 4 of pigmented polymer intowhich the picture is reflected.

In FIG. 2 a portion 5 of a projection screen for use in subdued lightingor total darkness comprises a backing 2 consisting of Melinex polyesterfilm, 0.001 inch thick mechanically brushed on one side 3 to provide ahairline surface, which is vacuum coated with aluminium, at 1.5 to 2.0ohms, and then overlaid with a transparent plastics film 6, 0.004 inchthick, having a brushed-silk surface 7 remote from the backing 2, withthe lines on both materials 2, 6 extending in the same direction.

The combination of the reflective hairline surface 3 and the brushedfinish 7 affords a brilliant picture with wide angle viewing (i.e.,anything up to 45) either way perpendicular to the lines (which,therefore, are usually employed in a vertical direction), and thebrushed surface 7 creates warm tones without detracting from thedefinition.

In FIG. 3, a rigid frame 8 is fonned of aluminium channel 9 with aslight flange 10 over which the material l of FIG. 1 or the material 5of FIG. 2 is stretched and secured by its margins 11 at theback of theframe, the channel 9 of the latter conveniently being utilised for thelocation of foamed plastics 12 affording stiffness without adding anyappreciable weight. The Melinex 2 is preferably heat shrunk, asdescribed in British Patent Specification No. 841,875, after stretchingover the frame 8 and securing at the back by the margins 11; in the caseof a daylight screen the material 1 as a whole may be affixed in thisway, while in the case of a screen for use in subdued lighting or totaldarkness the Melinex only is affixed in this way and the transparentfilm 6 is heated and stretched over the covered frame and then allowedto cool to tension the transparent film over the already tensionedMelinex.

' In FIG. 4 the material 1 for a daylight screen is shown secured to arigid support 13 of plastics material by adhesive applied marginally orall over, while in FIG. 5 the same material 1 is shown secured bypressure adhesive to a polyvinylchloride support material 14, 0.008 inchto 0.020 inch thick. Heat is not required for making the roll screen ofFIG. 5 and should be avoided. A roll screen may be converted to a fixedscreen by securing the roll screen to a rigid support or frame.

TEST RESULTS Comparative tests'have been carried out to establish andquantity the difference in performance between a standard matt surfacescreen and a daylight screen as described above. The test layout was asshown in FIG. 6, the lines of the hairline surface 3 being disposedvertical.

A. ILLUMINATION OR BRILLIANCE TEST For each screen the distance P of theprojector from the centre of the screen was 7 feet-6 inches and thedistance M of the light meter from the centre of the screen was 12feetinch from all readings Position of Light Meter 0 15 30 45 60Readings of'(Standard Screen 53 55 55 55 55 Light Meter (Daylight ScreenI I0 I00 90 70 60 increase in illumination I 82 64 27 B. DEFINITION ORRESOLUTION TEST Luminance Factor Ribbed Silver Screen for subdued FabricScreen lighting or total darkness Angle of Viewing What I claim is:

l. A projection screen comprising a backing having opposite surfaces,one of said surfaces being reflective, said reflective surface alsobeing provided with parallel lines to provide a hairline surfacethereon. and a matt overlay of transparent material over the hairlinesurface.

2. A projection screen according to claim I wherein the backing is arigid material scratched in parallel lines to provide the hairlinesurface and having aluminum as the reflective surface deposited thereon.

3. A projection screen according to claim 1 wherein the backing is sheetmetal material, one surface of which is reflective, and the reflectivesurface being scratched in parallel lines to provide the hairlinesurface.

4. The projection screen of claim 1 wherein the backing is a rigid sheetcoated on one surface with a reflective metal coating, and the metalcoating is scratched in parallel lines to provide the hairline surface.

5. The projection screen of claim 1 wherein the matt overlay oftransparent material is a plastic film.

6. The projection screen of claim 5 wherein the matt overlay oftransparent material is a pigmented solution of vinyl acetate/vinylalcohol copolymer in a mixture of ketones and hydrocarbons.

7. The projection screen of claim 1 wherein the surface of said backingopposite to the reflective surface is secured to a support.

8. The projection screen of claim 1 wherein the surface of said backingopposite the reflective surface is secured to a rigid frame.

9. The projection screen according to claim 1 wherein the matt overlayof transparent material comprises a transparent plastic film having abrushed exterior surface to provide lines thereon, with the linesthereof being aligned in the same direction as the lines in the hairlinesurface on the backing.

10. A projection screen according to claim 9 wherein the backing is arigid material scratched in parallel lines to provide the hairlinesurface and having aluminum as the reflective surface deposited thereon.

1 l. A projection screen according to claim 9 wherein the backing issheet metal material, one surface of which is reflective, the reflectivesurface being scratched in parallel lines to provide the hairlinesurface.

12. The projection screen of claim 9 wherein the backing is a rigidsheet coated on one surface with a reflective metal coating, and themetal coating is scratched in parallel lines to provide the hairlinesurface.

13. The projection screen of claim 9 wherein the matt overlay is aplastic film.

14. The projection screen of claim 13 wherein the matt overlay oftransparent material is a pigmented solution of vinyl acetate/vinylalcohol copolymer in a mixture of ketones and hydrocarbons.

15. The projection screen of claim 9 wherein the surface of said backingopposite to the reflective surface is secured to a support.

16. The projection screen of claim 9 wherein the surface of said backingopposite the reflective surface is secured to a rigid frame.

2. A projection screen according to claim 1 wherein the backing is arigid material scratched in parallel lines to provide the hairlinesurface and having aluminum as the reflective surface deposited thereon.3. A projection screen according to claim 1 wherein the backing is sheetmetal material, one surface of which is reflective, and the reflectivesurface being scratched in parallel lines to provide the hairlinesurface.
 4. The projection screen of claim 1 wherein the backing is arigid sheet coated on one surface with a reflective metal coating, andthe metal coating is scratched in parallel lines to provide the hairlinesurface.
 5. The projection screen of claim 1 wherein the matt overlay oftransparent material is a plastic film.
 6. The projection screen ofclaim 5 wherein the matt overlay of transparent material is a pigmentedsolution of vinyl acetate/vinyl alcohol copolymer in a mixture ofketones and hydrocarbons.
 7. The projection screen of claim 1 whereinthe surface of said backing opposite to the reflective surface issecured to a support.
 8. The projection screen of claim 1 wherein thesurface of said backing opposite the reflective surface is secured to arigid frame.
 9. The projection screen according to claim 1 wherein thematt overlay of transparent material comprises a transparent plasticfilm having a brushed exterior surface to provide lines thereon, withthe lines thereof being aligned in the same direction as the lines inthe hairline surface on the backing.
 10. A projection screen accordingto claim 9 wherein the backing is a rigid material scratched in parallellines to provide the hairline surface and having aluminum as thereflective surface deposited thereon.
 11. A projection screen accordingto claim 9 wherein the backing is sheet metal material, one surface ofwhich is reflective, the reflective surface being scratched in parallellines to provide the hairline surface.
 12. The projection screen ofclaim 9 wherein the backing is a rigid sheet coated on one surface witha reflective metal coating, and the metal coating is scratched inparallel lines to provide the hairline surface.
 13. The projectionscreen of claim 9 wherein the matt overlay is a plastic film.
 14. Theprojection screen of claim 13 wherein the matt overlay of transparentmaterial is a pigmented solution of vinyl acetate/vinyl alcoholcopolymer in a mixture of ketones and hydrocarbons.
 15. The projectionscreen of claim 9 wherein the surface of said backing opposite to thereflective surface is secured to a support.
 16. The projection screen ofclaim 9 wherein the surface of said backing opposite the reflectivesurface is secured to a rigid frame.